A magnetic head (hereinafter: perpendicular magnetic head) of a perpendicular magnetic recording system has a magnetic pole that generates a magnetic field for recording magnetic information in a recording medium. In order to prevent a magnetic field for recording from expanding and to prevent magnetic information that is already recorded in a recording medium from being unintentionally erased, a perpendicular magnetic head that has a shield layer for intaking (or collecting) magnetic flux in the surrounding area of a main magnetic pole is becoming mainstream.
There are three types of parts for the shield layer: (1) two side shield layers that are located at both sides of a magnetic pole in the track width direction, (2) a leading shield layer that is located at a leading side of the magnetic pole, and (3) a trailing shield layer that is located at a trailing side of the magnetic pole.
In an opposing medium surface that faces a recording medium, the main magnetic pole part is surrounded by these three types of the shield layers. A magnetic head in a, so-called, “around-shield” type discussed above and a method for manufacturing thereof are disclosed in U.S. patent publication No. 2008/0112081 (hereinafter: “patent reference 1”).
A method for manufacturing a perpendicular magnetic head disclosed in patent reference 1 is explained below with reference to FIG. 1. When a writing part of a recording head unit is formed in the method for manufacturing the perpendicular magnetic head, a leading shield layer 514 is formed as a base on an insulating layer 513. Then, a resist pattern (not shown) that has an opening part is formed on the leading shield layer 514. In order to form the resist pattern, after a resist film is formed on the leading shield layer 514, the opening part is formed by a photolithography method.
A nonmagnetic layer 515 is formed with a uniform thickness to cover at least an inner wall of the opening part in the resist film by using a dry film forming method. When the nonmagnetic layer 515 is formed, the surface (including the inside wall) of the resist pattern and the leading shield layer 514 that is exposed at the opening part are covered by the nonmagnetic layer 515.
Then, a main magnetic pole layer 540 is formed so as to fill the opening part in which the nonmagnetic layer 515 is formed. At the time of forming the main magnetic pole layer 540, a seed layer 516 and a plating layer 517 are formed as a magnetic layer for forming the main magnetic pole layer 540 so as to fill at least the opening part in which the nonmagnetic layer 515 is formed.
Subsequently, by removing the remaining resist pattern, the leading shield layer 514 is exposed on both sides of the main magnetic pole layer 540 in the track width direction (X direction in FIG. 1). Then, two side shield layers 518R and 518L are formed on both sides of the main magnetic pole layer 540 in the track width direction so as to be separated from the main magnetic pole layer 540 through the nonmagnetic layer 515, respectively.
At the final step, after a gap layer 519 as a nonmagnetic layer is formed on the nonmagnetic layer 515, the main magnetic pole layer 540, and the two side shield layers 518R and 518L by, for example, using a sputtering method, a trailing shield layer 520 is formed on the gap layer 519. As a result, a writing part of a recording head part is completed.
However, with respect to the manufacturing method for making the opening part at the resist discussed above, because the photolithography process is performed on the resist film that is directly formed on the leading shield layer 514 that is made of a metal, the resist is, for example, exposed again by light that is reflected at the leading shield layer 514 at the time of the exposure so that a phenomena, such as halation, that worsen shapes of the opening part may occur. When the halation occurs, the opening part cannot be formed in the desired shapes. As a result, there are problems such as: shapes of the main magnetic pole layer 540 cannot be controlled, and performance as a writing element is lowered.
When the shapes of the main magnetic pole layer 540 are controlled by adjusting a layer thickness of the nonmagnetic layer 515 that is formed on the inside wall of the opening part in the resist, there is a problem in that the layer thickness of the nonmagnetic layer 515 varies location by location so that functions of the shield layers 514, 518L, and 518R that are formed around of the nonmagnetic layer 515 are lowered.
As one of the measures to resolve these problems, a halation prevention nonmagnetic layer 515A that prevents the halation can be formed on the leading shield layer 514 before the resist is formed on the leading shield layer 514. In this case, after a resist pattern is formed on the halation prevention nonmagnetic layer 515A, the main magnetic pole layer 540 is formed on the halation prevention nonmagnetic layer 515A by using the same method as discussed above. The magnetic head formed through the method discussed above is shown in FIG. 3.
In the case of using the halation prevention nonmagnetic layer 515A, when the remaining resist pattern is removed after the main magnetic pole layer 540 is formed, the halation prevention nonmagnetic layer 515A formed on the leading shield layer 514 is exposed at both sides of the main magnetic pole payer 540 in the track width direction (X direction in FIG. 3) (see FIG. 2). Therefore, because the leading shield layer 514 magnetically connects to the side shield layers 518L and 518R that are formed next, it is necessary that the halation prevention nonmagnetic layer 515A that is exposed on both sides of the main magnetic pole layer 540 is removed.
However, the inventors of the present invention realized that patent reference 1 still has a problem discussed below as a result of testing and investigation. Because the main magnetic pole layer 540 and the halation prevention nonmagnetic layer 515A surrounding thereof have a tiny structure, it is hard to completely remove the halation prevention nonmagnetic layer 515A. Therefore, as shown in FIG. 3, a part 515E of the halation prevention nonmagnetic layer 515A that exists between the main magnetic pole layer 540 and the leading shield layer 514 remains. A gap between the main magnetic pole layer 540 and the shield layers 514, 518L, and 518R is not uniform. As a result, because the shield layers 514, 518L, and 518R have a sharp-pointed part, the magnetic field is concentrated at that part, so that a problem of decreasing the functions of the shield layers 514, 518L, and 518R as a shield layer occurs. As discussed above, performance as a writing element is lowered.
Therefore, it is desired to provide a method of manufacturing a perpendicular magnetic head in which performance of a writing element can be improved by keeping a gap between a shield layer and a main magnetic pole layer as uniform as possible.